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Adhesion of mussel foot proteins to different substrate surfaces
Lu, Qingye,Danner, Eric,Waite, J. Herbert,Israelachvili, Jacob N.,Zeng, Hongbo,Hwang, Dong Soo The Royal Society 2013 Journal of the Royal Society, Interface Vol.10 No.79
<P> Mussel foot proteins (mfps) have been investigated as a source of inspiration for the design of underwater coatings and adhesives. Recent analysis of various mfps by a surface forces apparatus (SFA) revealed that mfp-1 functions as a coating, whereas mfp-3 and mfp-5 resemble adhesive primers on mica surfaces. To further refine and elaborate the surface properties of mfps, the force-distance profiles of the interactions between thin mfp (i.e. mfp-1, mfp-3 or mfp-5) films and four different surface chemistries, namely mica, silicon dioxide, polymethylmethacrylate and polystyrene, were measured by an SFA. The results indicate that the adhesion was exquisitely dependent on the mfp tested, the substrate surface chemistry and the contact time. Such studies are essential for understanding the adhesive versatility of mfps and related/similar adhesion proteins, and for translating this versatility into a new generation of coatings and (including <I>in vivo</I> ) adhesive materials. </P>
Asymmetric Collapse in Biomimetic Complex Coacervates Revealed by Local Polymer and Water Dynamics
Ortony, Julia H.,Hwang, Dong Soo,Franck, John M.,Waite, J. Herbert,Han, Songi American Chemical Society 2013 Biomacromolecules Vol.14 No.5
<P>Complex coacervation is a phenomenon characterized by the association of oppositely charged polyelectrolytes into micrometer-scale liquid condensates. This process is the purported first step in the formation of underwater adhesives by sessile marine organisms, as well as the process harnessed for the formation of new synthetic and protein-based contemporary materials. Efforts to understand the physical nature of complex coacervates are important for developing robust adhesives, injectable materials, or novel drug delivery vehicles for biomedical applications; however, their internal fluidity necessitates the use of in situ characterization strategies of their local dynamic properties, capabilities not offered by conventional techniques such as X-ray scattering, microscopy, or bulk rheological measurements. Herein, we employ the novel magnetic resonance technique Overhauser dynamic nuclear polarization enhanced nuclear magnetic resonance (DNP), together with electron paramagnetic resonance (EPR) line shape analysis, to concurrently quantify local molecular and hydration dynamics, with species- and site-specificity. We observe striking differences in the structure and dynamics of the protein-based biomimetic complex coacervates from their synthetic analogues, which is an asymmetric collapse of the polyelectrolyte constituents. From this study we suggest charge heterogeneity within a given polyelectrolyte chain to be an important parameter by which the internal structure of complex coacervates may be tuned. Acquiring molecular-level insight to the internal structure and dynamics of dynamic polymer complexes in water through the in situ characterization of site- and species-specific local polymer and hydration dynamics should be a promising general approach that has not been widely employed for materials characterization.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/bomaf6/2013/bomaf6.2013.14.issue-5/bm4000579/production/images/medium/bm-2013-000579_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/bm4000579'>ACS Electronic Supporting Info</A></P>
Adhesion mechanism in a DOPA-deficient foot protein from green mussels
Hwang, Dong Soo,Zeng, Hongbo,Lu, Qingye,Israelachvili, Jacob,Waite, J. Herbert The Royal Society of Chemistry 2012 SOFT MATTER Vol.8 No.20
<P>The holdfast or byssus of Asian green mussels, <I>Perna viridis</I>, contains a foot protein, pvfp-1, that differs in two respects from all other known adhesive mussel foot proteins (mfp): (1) instead of the hallmark <SMALL>L</SMALL>-3,4-dihydroxyphenylalanine (DOPA) residues in mfp-1, for example, pvfp-1 contains C<SUP>2</SUP>-mannosyl-7-hydroxytryptophan (Man7OHTrp). (2) In addition, pvfp-1 chains are not monomeric like mfp-1 but trimerized by collagen and coiled-coil domains near the carboxy terminus after a typical domain of tandemly repeated decapeptides. Here, the contribution of these peculiarities to adhesion was examined using a surface forces apparatus (SFA). Unlike previously studied mfp-1s, pvfp-1 showed significant adhesion to mica and, in symmetric pvfp-1 films, substantial cohesive interactions were present at pH 5.5. The role of Man7OHTrp in adhesion is not clear, and a DOPA-like role for Man7OHTrp in metal complexation (<I>e.g.</I>, Cu<SUP>2+</SUP>, Fe<SUP>3+</SUP>) was not observed. Instead, cation–π interactions with low desolvation penalty between Man7OHTrp and lysyl side chains and conformational changes (raveling and unraveling of collagen helix and coiled-coil domains) are the best explanations for the strong adhesion between pvfp-1 monomolecular films. The strong adhesion mechanism induced by cation–π interactions and conformational changes in pvfp-1 provides new insights for the development of biomimetic underwater adhesives.</P> <P>Graphic Abstract</P><P>Molecular interactions of a DOPA-deficient foot protein from green mussels, pvfp-1, were measured using a surface forces apparatus (SFA). The strong adhesion mechanism induced by cation–π interactions and conformational changes in pvfp-1 provides new insights for the development of biomimetic underwater adhesives. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2sm25173f'> </P>
Mussel foot protein-1 (mcfp-1) interaction with titania surfaces
Hwang, Dong Soo,Harrington, Matthew J.,Lu, Qingye,Masic, Admir,Zeng, Hongbo,Waite, J. Herbert The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.31
<P>Marine mussels utilize a variety of DOPA-rich proteins for purposes of underwater adhesion, as well as for creating hard and flexible surface coatings for their tough and stretchy byssal fibers. In the present study, moderately strong, yet reversible wet adhesion between the protective mussel coating protein, mcfp-1, and amorphous titania was measured with a surface force apparatus (SFA). In parallel, resonance Raman spectroscopy was employed to identify the presence of bidentate DOPA–Ti coordination bonds at the TiO<SUB>2</SUB>–protein interface, suggesting that catechol–TiO<SUB>2</SUB> complexation contributes to the observed reversible wet adhesion. These results have important implications for the design of protective coatings on TiO<SUB>2</SUB>.</P> <P>Graphic Abstract</P><P>Moderately strong, yet reversible wet adhesion between mussel coating protein and titania was measured with a SFA and Raman spectroscopy. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm32439c'> </P>